Signaling system



July 7, 1925.

J. C. SCHELLENG SIGNALNG SYSTEM Fied Nov. 24, i922' /nVen/or John C. Syd/eng. by A/fy.

@Rm VOLTAGE DE Panarea July 7, i925.

- .UNITED Us'rATEs PATENT carica.

JOHN c. scHELLENG, or EAST ORANGE, NEW JERSEY, AssIGNoR To WESTERN ELEC- 'raro COMPANY, INcoEroEA'rED, 0E NEW YORK, N. Y., a CORPORATION oE'NEw YORK.

sIeNALiNG sYsa'EM.

Applicatton tiled November 24, 1922. Serial No. 602,949.

To all whom it may concern.

' Be Lit .known that-I, JOHN C. SCHELLENG, a` citizenof the. United States, residin at East Orange,in the county loflssex', tate of New Jersey, have Ainvented certa-in new and useful Improvements in Signaling Systems, of which the 4following isa full, clear, concise, and exactdesciiptio This invention relates tol'signaling systems and particularl to apparatus for quse 4in connectionk with t e control of signaling circuits such as telegraph circuits.

Itisv an object of the present invention to cause, in response to signaling impulses, the operation of a pair of electron discharge devices having their input electrodes oppositely connected tp a-signaling path -and ad- Justed in a manner such that for predetermined charges on the input'electrodes different current changes' areproduced 'in the outputcircuit thereby causing the differentlal effect of such current. changes.

In accordance with the above and other objects, there is provided a pair of vacuum tubes of the three-element type having their input circuits connected oppositely to a signaling'path. In each vof the input circuits, there is connected a resistance of several megobms', whereby with the charge on the control electrode of the tubes normally positive and tubes ad'usted to normally work on the point of t e grid voltage and output current characteristic having the greatest' curvature, the resistance of the grid filament circuit of the one tube becomes small while the resistance of the ,grid filament circuit of the other tube becomes very large. With such an arrangement, with a corresponding change in the voltage, the increase in'space current'of the one tube is small while the current decrease of the other tube is comparatively large.' This results in su erior operation, giving a high degree of e ciency in the detection of. sigpulse irrespective of the polarity ofthe im- 1 ulses received on the input circuit of the rubc combination. i

In the drawingfFig. 1 illustrates diagrammatically one embodiment of the invention. Fig. 2 shows a modification of the .n1-rangement shown in Fig. 1. Fig. 3 is a curve characteristic of one of the .tubes with output current plotted against grid voltage.

In Fig. 1. a receiving antenna l is connected serially with a foil 5. This coil 5 serves to impress signal on coilV 6. Coil:6 is connected in the grid filament circuits .pf a pair of three-element vacuum tubes 7 and 8 connected in al manner whereby the tiglbes have their input electrodes associated with the signaling path in pushpull relation. l` he terni push-pull, asusegi .in the present instance` refers to an ar'raxigement of vacuum tubes in which their input or grid electrodes are associated with the signaling path oppositely. .()neend of thecoil 6 is -V directly connected Vwith the grid electrode 9` of tube B, while the other end thereof is connected to thegrid electrode 10 of tube 7. A condenser 13 is cermccted across the ter" minals of' the. coil 6 to increase the selectivity of the system. Also connected across the termina-ls of the coil 6 and between the grid electrodes 9 and 10, and having-'a terminal connected with filaments 11 and 12 of tubes 7 and S respectively, area pair as. for example, when the `rid electrode 10 is made positive with respect to the filament 11, only a small portion of the current Hows through the .resistance 14, the greater portion thereof flowing between the grid 10 and the filament 11 and'then through the resis tance 15. Atthe saine time grid 9 of tube 8 becomes at least as negative as -the cathode, andthe internal impedance of the tube 9 becomes substantially infinite.

In the output circuits of the tubes 7 and i 8 which extend between the plate electrodes 16-and 17 and the filaments .11 and 12 is a battery 18 and a telephone receiver 19. A condenser`20 may be shunted around the rcceiver 19.1l`

The arrangement just described may be employed for detectin different kinds of signaling impulses as, or example, damped wave trainsor voice or signal modulated continuous trains Iof waves. In the case of damped wave trains, each train owaves.

noy

changes the normal charge on the grid electrodes which, in the preferred form of the invention, is made normally positive. The

-waves thus received'are' impressed onthe control electrodes vof/each of the tubes- Thus, when afwave is impressed on coil 6,

, which produces a voltage in the direction of the solid arrow, the grid electrode 10 vof tube '7 is made more positive, while grid electrode 9 of'tube 8 is made less positive or negative withrespect to the cathode. The result of this will be an increase in 'fthe electrons flowing between cathode ll and plate 16, while the. opposite effect is reduced in tube 8,-that is, thespaee current in. thvisftube is decreased. The decrease in 'the currentfof tube 8 is greater than the 'jiiicease in .tube 7 due to two effects, one

'f'.that the voltage change on the more nega- Ltive id 9 is greater" due to the greater impe ance on .which it is derived, and the fotlrerrtliatutlie tubes may `be .operated on l'cuiv'd portio'n'of ,the natural characterfistic'fthegtiibeslf The circuit of such current may be traced-"from '.tlie upper terminal of co i l "tofj'thep'intin which the resistance 14 andfthe grid electrode 10 are connected. Owing to `the value of this resistance, only .a "very'sjmall portion of the'1 current fiows' Atherethroughf-'the greater portion of the cur rent flowing hetwcciiltlie gridy 10 andcathode 11,- the rcsistance'-1i ,andi'ithe turnsot coil 6 to, .l.,the` pointjrom-which the circuit was Nowfif an impulse isimpressed on the coil 6 ',causing.; avoltage in the direction of the dotted arrow, a -result opposite to that just described-is produced as, for example, the space'current through tube 8 increases while that through tube 7 decreases in aci cordance with the' condition just described.

' The currentinithe output circuit. including the-receiver'l9'is varied but will he in thc same direction irrespective 'of the character of the impulses impressed on coil'G.

The primary purpose of the connection of resistances 14 and 15 in the grid filament circuits of tubcs? and 8 is to secure the maximum detecting action. In other words,

` it is desired toobtain the maximum change plate current, while curve B re resents the' grid current curve characteristic with the addition of the current flow through the input resistance when the grid of such tube is made positive. The line drawn below the axis and designated as C represents the currentv 'flow through the resistance connected in bridgeof the 'input'Av circuit of the tube, the grid of' which becomes negatively charged for such condition.

For example, suppose a voltagerE is impressed between-the grids of-'tubcsfand 8,. the components of vthis voltage'f when the tubes 7 and 8 are made positive and negative respectively, are El and E2, as shown by the curve of Fig. 3. l" or this condition, a current equal to vD flows in theinput circuit of tube 7 lwhile the current through the resistance 15 of tube 23 is of an, equal value D since the 'space current is zero when thc grid of tube 8 is negative. ABy applying the voltageA E to the output current curve charlactcrist-ic A, it is Seen that rvthecurrent in tube 7, dueto voltage El, is of a value equal to b while for theftube 8, the current is equal to c. l 'lhe current change in Atube 7 being positive and that intube 8 being negative, the rectification ede'ct ofthe tube combination is equal to-the al ,ebraic sum of these two currentchanges. L 4'rvcs'Band C are plotted assuming that'the normal grid voltage is zero or negligibly positive.; Either oneof these curves gives the current, in thepair of wires crossing broken li'ne'avFF (Fig. l), a current tothe right being considered positive and one to the letnegative. It is seen that to the right-of line FF the current may have one or more'branclies Adependl ing upon whether current ma flow from grid to filament, that is, whet er the grid of the tube considered is positive or nega- 'tive 'th respect to its filament. formez1 casethe curve liesto the right of the origin andis the sum of two parts, first, the grid current, a rapidly risingline concave upward, and second, that through the shunt resistance this being a -straight line througlrthe origin; in the latter case the line lies to the left of the origin `because of the negative potential and below the line because the direction of the current also is reversed. The latter line is straight because In the' les when the current is negative no current"- Hows to it; the current across FF is, there fore, only that through the shunt resistance. Since the total ,current obtained by taking the algebraic sum of two. currents across line F must beezero, the current at g is opposite that at L. This condition being true, the grid potentials resulting from applications of E must besuch as to give these equal currents which in the diagraml (Fig.

3) are D and D.. It is now also obvious from ,the diagrams that to do this the grid tentials of the twotubes must be opposite m sign and'unequal. in magnitude.v The o'pchange of plate current..` Thezinequality of i posi'tene of 'sign leads tooppositeness of.

magnitudel leads directly to inequality in plate current which leads to rectification in this circuit. It is evident from the straightbe present in the grid voltage thus leading to a resultant change in the total plate current. It is evident Jfrom curve A that the rectification effect is greater' as described j than it would be from a circuit which depended for rectification on the curvature of curve A.

In the modification shown in Fig. 2, like parts are represented by the same reference characteristics with the prime indices added. A pair of vacuum tubes of the three-element type 7 and 8' have their grid electrodes connected with conductors 34 and 35, .respectively, which extend from a distant station at v ihich transmitting apparatus, such as the' .ifey 36, for transmitting impulses in accoroance with a desired message, is located. To produce. the same results obtained in 'connectiOn with the arrangement shown in Fig.

l, the input circuit of eachof the tubes is bridged by a resistance of several megohms. Con ected in the output circuit of the tubes 'ii' and 8 is a polarized relay 25 comprisin"l a soft iron magnetic core 26 having a pair' of pole pieces 27 and 28. Surrounding fthese pole pieces are magnetizing windings29 and 30. These niagnetizing windings, are connected serially with the output circuit of the vacuum tuhes 7 and 8. Pivoted to the core 26 is an armature 3l which is adapted `to swing between pole pieces 27 and 28 and cooperates with a pair of oppositely disposed contacts. Attached to the tree end of the armature. 31 is a spring 32 which serves to bias the armature 3l in its normal position. `With such an arrangement, a' relay is provided which has three positions, that is, the armature may he in engagement' with either of its contacts or in the central or neutral position, as determined hy the character ot' the received im.- pulse and the spring The line conductors 34 and have serially connected therewith an operating winding 33 which encircles the armature 3l and serves to magnetize the armature that it may be attracted by either pole piece. 27 or 28, depending upon the polarity of the imp'ulse traversingfthis winding.

With the arrangement shown in the drawing, space current normally flows through the tubes 7- and 8 which would cause a corresponding fiow of current through the magnetizing windings 29 and 30. To compensate for this current flow whereby the current through the magnetizing windingsl i 29 and 30 is reduced substantially to zero' during the non-reception of signals, the magnetizing windings have connected in bridge thereof aninductance 38, an adjustable resistance 39 and a battery 40. This combination of elements composes an arrangement whereby the elect of the normal space current in the tubes -7' and 8' may be balanced thereby reducing the polarizing current, through the relay 25, to a small value.

`When the` key 36 is operated to connect the positive terminal of battery 37 with the line conductor 34, an impulse of a positive character flows over the line conductor 34 andcharges the grid electrode 10 ot tube 7' more positively Aand also in its continued flow passes through operating winding 33`of relay 25. The making of the grid electrode -10 of tube 7 more positive with respect to the filament electrode 11 increases the space current through this tube in a" manner simi lar to that disclosed in connection with Fig. 1. Also, the'gridclectrode 9': of tuheB for the condition selected is made m'ore negative ywith respect to ,theglament electrode 12',

whereby the current in this tube decreases, thus causing a corresponding change in the current i n the output circuit of. the tube combination. The introductionof the resist- :luces-14 and 15 inlthe input circuits of these tubes produces an eect in which the impedance of the grid filament circuit of the tubes 7 is made relatively small, while the impedance of the grid filament Vcircuit of the tube 8 is made comparatively large. The current flowing through the magnetizing windings 29.a.nd 30 is thereupon increased, the effect of which, together with the current of a positive polarity which {'lowsthrough -the winding 33, armature 31 is moved to engage the upper contact.

Should the key 36 be operated in a manner to connect-.the negative pole of battery 37 with the conductor 34, a condition opposite to, that just described will exist.

It is to be noted, however, in the two conditions selected, the current in the output circuit of the tubes 7 and 8 is in the same direction, that is, the direction of the current `in the output' circuit of the tubes 7 and 8 is in the same direction irrespective of the character of the impulse impressed on the line conductors 34 and 35 which causes thel operation of the tubes 7 and 8 in a manner similar to that described in connection with Fig. 1.

When current is allowed to flow through the magnetizing windings 29 and 30, the armature 31 will swing toward the pole piece 27 when a positive impulse is impressed on the line conductors, and will swing in the opposite direction when a negative impulse is transmitted.

The invention claimed is:

1. A signaling system comprising a signaling path, a air of electron discharge devices asociatedJ with said signaling path, each of said devices having a cathode, an anode and a control electrode, means for maintaining said control electrode at least Aas positive Vas the cathode electrode such thatthe de/vices are working near a point 'of maximum rectification, and a path to which 'input potentials 'are to .beapplied connect- 2. A signalingfsystem comprising la signaling. path, apair .of electron discharge devices asociated 'with said signaling path.

each 'of said -devices having. a cathode, an anode and a control electrode, -means formaintaining said control electrodes at least as positive as the cathode electrodes thereof 'such' that the devices are working near a point of maximum rectification, a path te which -input potentials are to be applied connecting said cathode and control elec'- trodes including shunt resistances of a value sufficient to produce different voltage drops across the respective tubes-for a given signal impulse, and means in the output circuit re.

sponsive to the differential current. effect therein due to vsaid different voltages.

3. A signaling system comprising a sigmaling path, a pair of vacuum tubes having cathode, anode and grid electrodes withtlie grid'electrodes connected oppositely to said signalingr paths, a branch common -to thev anode electrodes of. said tubes, means for normally maintaining saidgrid electrodes at least as -positive as the cathode electrodes thereof such that the devices are working near a point of maximum' rectification, a path to which input potentials are to be applied including shunt resistance's of several niefrohms, whereby different voltage drops across the respective tubes is produced for a given signa-l impulse, and means in the com,- mon branch of the output circuit responsive to such differential e'ect. v

4. In combination, a source of positive and negative impulses, a pair of vacuum tubes responsive to impulses transmitted from said source, each of said tubes having a cathode, an anode and a grid electrode, means for maintaining said grid electrodes normally positive, whereby current normally flows in the output circuitV of said tubes, a relay connected in the output circuit of 'said tubes comprising operating -and magnetizing, windings, said'magnetizing windings being included iii the output circuit of said tubes, and means associated with saidrelay and tubes for reduc' thecurrent in said output circuit during '.non-signaling periods substantially to zero'.

5. In combination, 'a source of electric im-'.

pulses. of opposite clarity, a pair of threeelement electron iscliarge devices having their input electrodes connected oppositely" impulses are repeated.

in series with each oltheifacross'saidfsource, 65.

an outputcircuit having;A a common branch,`J .means for' causing said tubes' to vwork ontlie' portion of the input voltage'aid output current cliaracteristicfof the'greatest curvature and whereby different voltage 'drops are pro? '75l Y duced across the respectivetubes', and a po-` larized relay having' its'magiietizing wind: ings connected in 'the .common branch 'f of' said output circuit in which unidirectional 6. In combination, a source of electric irnpulses of opposite polarity, a pair of vac' uum tubes having cathode, anode andgi'id electrodes, the grid electrodes bein oppo' .sitely connected in series with eaci other '80 across said source, means for charging said. grid electrodes whereby space current nor- 1- mally fiows in the tubesduring 'nonsigiialing intervals, anoutput circuit, and means whereby different. voltage drops are pro- -fduced across the respective tubes to cause the differential elfect of current changes due; to said dili'crent voltages to be applied to said output circuit.

pulses of opposite polarity, a pair' of vac uum tubes having cathode, anode and grid electrodes the grid electrodes being'oppositely connected in series with eachother across said source, an output circuit having a common branch and a path to which such impulses y are to be applied connecting saidcathode aud grid electrodes including shunt resistances of suoli value to produce dilier-` ent voltage drops across the respective tubes 19 for a given signal impulse to cause the dif-v ferential current eli'ects to be applied to said common branch due to said different volta es.

g8. In combination, a source of electric impulses of opposite polarity, a pair of vacl uuintubes having cathode, anode and grid electrodes, the grid electrodes being opposive to the operation of said `vacuum tubes U5 having operating and magnetiziiig windings, said magnetizing windings being ineluded in the common branchpf said output circuit, and means whereby different voltage drops are produced across saidtubes fora given signal impulse to cause' the differen-4 tial efiects to be ap lied to the inagnctizing windings of said re ay dueto' said different voltages. f

In Witness whereof, I'hereunto subscribe 125 -my name'this 22nd day of November A. D.,

JOHN C. sciinLLuNo.

i. In combination, a-source of-clectric im- 904 Y 

